Various shoulder joint implant art is known, to include ensembles for total or perhaps partial joint replacement of the main shoulder joint, i.e., the glenohumeral joint. Conventional configurations of those attempt to mimic the natural glenohumeral joint, generally having an implanted artificial humeral component with a ball-like head, say, of metal or ceramic, which articulates in and against a generally shallow open cup, say, of polyethylene or metal, of an implanted artificial glenoid component in a total arthroplasty or perhaps against the natural glenoid cup in a hemiarthroplasty. As good as such art can be, it is not without its drawbacks. Among these are difficulties in achieving natural range of motion; and the shoulder—being an enarthrodial joint, and the joint of the body with the greatest range of motion as in nature its head is held in place to a great extent by means of muscle, fibrous capsule and ligamentous tendon structures in a shallow cup, i.e., the glenoid cup—can be prone to dislocation, even after joint replacement surgery with a device of such art. The most frequent cause of unsuccessful shoulder joint replacement is failure of fixation through loosening of glenoid components, not infrequently caused by compromise of mounting of a metal shell holding the cup, or compromise of a cemented plastic cup, to a surgically prepared portion on the quite thin and fragile scapular bone, i.e., glenoid area. This deficit of glenoid area supporting bone may need to be addressed. Reverse shoulder implants are also known, in which a ball head is provided as part of the glenoid component, with a corresponding cup as part of the humeral component. Such art, too, is not without drawbacks, among which may include dislocation and/or glenoid component loosening as with the more anatomically conventional shoulder joint implants discussed in general above. Compare, the following art:    U.S. Pat. No. 4,550,450 to Kinnett, for a total shoulder prosthesis system.    U.S. Pat. No. 6,248,132 B1 to Harris, for a hip replacement prosthesis.    U.S. Pat. No. 6,953,478 B2 to Bouttens et al. for a shoulder prosthesis assembly.    U.S. Pat. No. 7,959,680 B2 to Stone et al., for a method and apparatus for performing a shoulder implant procedure.    Publication No. US 2004/0039449 A1 of Tornier, for a shoulder or hip prosthesis facilitating abduction.    Publication No. US 2006/0079963 A1 of Hansen, for a semi-constrained shoulder prosthetic for treatment of rotator cuff arthroplasty.    Murphy, L., and Prendergast, P., J. Biomechanics, 38 (2005), pages 1702-1711, “Acromion-fixation of glenoid components in total shoulder arthroplasty.”
In address of the foregoing, U.S. Pat. No. 9,561,111 B1 to Goodman—which is incorporated herein by reference in its entirety, to include its drawings—discloses a shoulder joint implant. It captures or fixes humeral and glenoid components and employs a yoke-containing universal joint connection. As excellent as the art of that Goodman patent is, it, too, is not without drawbacks. Among these are, in certain embodiments, a potential for substantial scar-tissue ingrowth, and possible pathogenic growth; a tendency to require resection of a substantial amount of bone; and a certain bulkiness, especially in encapsulated embodiments.
It would be desirable to improve upon the art. It would be desirable, in particular, to provide a shoulder joint implant that ameliorates if not solves in general one or more of the problems in the art, notably dislocation, loosening and/or supporting bone deficit of the glenoid area, and range of motion. Furthermore, it would be desirable to reduce any potential for possibly detrimental scar-tissue ingrowth, and possible pathogenic growth; to conserve bone; and to streamline the configuration and maintain a more limited size of the implant. Additionally, it would be desirable to provide alternative(s) to the art.